Tech/maintenance Why does a saxophone make its sound?

[David Dorning]

Simplistic version:
Airflow between reed and mouthpiece lowers the pressure, causing reed to bend closed from air and lip pressure. Closing stops the airflow, causing a drop in pressure, creating low pressure part of sound wave. Wave is reflected by first open tone hole back to mouthpiece. High pressure pulse opens reed. Frequency of reed vibration matches frequency of note, so the pressure oscillations maintain/reinforce the standing wave.

Thanks Kev, I think we are pretty well saying the same thing. I did say it was my understanding of a single reed, I haven't given any serious thought to flutes and recorders. Turbulent airflow produced by blowing across an aperture is obviously generated differently as pointed out by @nigeld. I found some interesting information some time ago in a paper from (I think) Macquarie University which filled in my understanding to the extent that I do understand it.... I'm still a bit vague on the idea of the reflected wave (pressure wave?), and physically why it comes back to the mp and how the whole thing relates to a standing wave. I'm assuming the pressure wave moves down the tube, leaving reduced pressure in the enclosed space until its energy is released at the first tonehole, then atmospheric pressure pushes everything back towards the mp and it all starts over again.

This is me thinking aloud and trying to form a model of what happens. Does anyone think that makes sense? Or that it doesn't?

 

[Eoe]

Yeah it's a Brain Buster. So from my research and what I do in my training. You feel your lungs up with as much air as possible. You use your epigetotts to hold this pressure back and together with your diaphragm build as much pressure as you can then you bring this pressure through your vocal cords affecting the pressure and tone. Then finally to your mouth where you control the pressure with your mouth shape and then you let it affect the read.

 

[Colin the Bear]

A sicentific exlpanation with pytos, splingleling mistakes and roop griimmer makes no sense

 

[Eoe]

Aw bless his heart

 

[jbtsax]

A fascinating part of all this is that the air column inside the instrument and the reed cooperate to form a "regime of oscillation" as Benade calls it. This describes the vibrations of the fundamental and all of its harmonics. If "inharmonicity" is present which means that not all of the frequencies of the harmonics generated are exact whole number multiples of the frequency of the fundamental, then those "out of tune" harmonics move from their peak amplitude to lock into frequencies that are whole number multiples of the fundamental. This process is called "mode locking". The more "mode locking" occurs, the more energy is lost by harmonics moving from their "out of tune" peaks to a frequency with less amplitude.

When a saxophone or other woodwind exhibits good "harmonicity" on all of the notes in its range, the player senses an instrument that has a good response, has a rich, full tone, and demonstrates good intonation. It is also an instrument that the player can "push" to a wider dynamic range.